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Lookup NU author(s): Rachel Gray, Dr Evelyn JensenORCiD
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).
© The Author(s) 2024. Published by Oxford University Press on behalf of The Society for the Study of Evolution (SSE).Galapagos giant tortoises are endemic to the Galapagos Archipelago, where they are found in isolated populations. While these populations are widely considered distinguishable in morphology, behavior, and genetics, the recent divergence of these taxa has made their status as species controversial. Here, we apply multispecies coalescent methods for species delimitation to whole-genome resequencing data from 38 tortoises across all 13 extant taxa to assess support for delimiting these taxa as species. In contrast to previous studies based solely on divergence time, we find strong evidence to reject the hypothesis that all Galapagos giant tortoises belong to a single species. Instead, a conservative interpretation of model-based and divergence-based results indicates that these taxa form a species complex consisting of a minimum of 9 species, with most analyses supporting 13 species. There is mixed support for the species status of taxa living on the same island, with some methods suggesting multiple populations of a single species per island. These results make clear that Galapagos giant tortoise taxa represent different stages in the process of speciation, with some taxa further along in that evolutionary process than others. Our study provides insight into the complex process of speciation on islands, which is urgently needed given the threatened status of island species around the world.
Author(s): Gaughran SJ, Gray R, Ochoa A, Jones M, Fusco N, Miller JM, Poulakakis N, de Queiroz K, Caccone A, Jensen EL
Publication type: Article
Publication status: Published
Journal: Evolution
Year: 2025
Volume: 79
Issue: 2
Pages: 296-308
Print publication date: 01/02/2025
Online publication date: 16/11/2024
Acceptance date: 14/11/2024
Date deposited: 03/03/2025
ISSN (print): 0014-3820
ISSN (electronic): 1558-5646
Publisher: Oxford University Press
URL: https://doi.org/10.1093/evolut/qpae164
DOI: 10.1093/evolut/qpae164
Data Access Statement: The whole-genome resequencing data from Jensen et al. (2022) are available under NCBI BioProject PRJNA761229. Code for running BPP and PHRAPL is available at: https:// github.com/sjgaughran/tortoise-species-delimitation. Code, control fles, aligned loci, and output fles for the analyses are available on Dryad at DOI: 10.5061/dryad.b2rbnzsqs.
PubMed id: 39548869
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